/**
 * @license Copyright (c) 2003-2013, CKSource - Frederico Knabben. All rights reserved.
 * For licensing, see LICENSE.html or http://ckeditor.com/license
 */

/**
 * @fileOverview AutoGrow plugin.
 */

(function() {

    // Actual content height, figured out by appending check the last element's document position.
    function contentHeight( scrollable ) {
        var overflowY = scrollable.getStyle( 'overflow-y' );

        var doc = scrollable.getDocument();
        // Create a temporary marker element.
        var marker = CKEDITOR.dom.element.createFromHtml( '<span style="margin:0;padding:0;border:0;clear:both;width:1px;height:1px;display:block;">' + ( CKEDITOR.env.webkit ? '&nbsp;' : '' ) + '</span>', doc );
        doc[ CKEDITOR.env.ie ? 'getBody' : 'getDocumentElement' ]().append( marker );

        var height = marker.getDocumentPosition( doc ).y + marker.$.offsetHeight;
        marker.remove();
        scrollable.setStyle( 'overflow-y', overflowY );
        return height;
    }

    function getScrollable( editor ) {
        var doc = editor.document,
            body = doc.getBody(),
            htmlElement = doc.getDocumentElement();

        // Quirks mode overflows body, standards overflows document element
        return doc.$.compatMode == 'BackCompat' ? body : htmlElement;
    }

    // @param editor
    // @param {Number} lastHeight The last height set by autogrow.
    // @returns {Number} New height if has been changed, or the passed `lastHeight`.
    var resizeEditor = function( editor, lastHeight ) {
        if ( !editor.window )
            return;

        var maximize = editor.getCommand( 'maximize' );
        // Disable autogrow when the editor is maximized .(#6339)
        if( maximize && maximize.state == CKEDITOR.TRISTATE_ON )
            return;

        var scrollable = getScrollable( editor ),
            currentHeight = editor.window.getViewPaneSize().height,
            newHeight = contentHeight( scrollable );

        // Additional space specified by user.
        newHeight += ( editor.config.autoGrow_bottomSpace || 0 );

        var min = editor.config.autoGrow_minHeight != undefined ? editor.config.autoGrow_minHeight : 200,
            max = editor.config.autoGrow_maxHeight || Infinity;

        newHeight = Math.max( newHeight, min );
        newHeight = Math.min( newHeight, max );

        // #10196 Do not resize editor if new height is equal
        // to the one set by previous resizeEditor() call.
        if ( newHeight != currentHeight && lastHeight != newHeight ) {
            newHeight = editor.fire( 'autoGrow', { currentHeight: currentHeight, newHeight: newHeight } ).newHeight;
            editor.resize( editor.container.getStyle( 'width' ), newHeight, true );
            lastHeight = newHeight;
        }

        if ( scrollable.$.scrollHeight > scrollable.$.clientHeight && newHeight < max )
            scrollable.setStyle( 'overflow-y', 'hidden' );
        else
            scrollable.removeStyle( 'overflow-y' );

        return lastHeight;
    };

    CKEDITOR.plugins.add( 'autogrow', {
        init: function( editor ) {

            // This feature is available only for themed ui instance.
            if ( editor.elementMode == CKEDITOR.ELEMENT_MODE_INLINE )
                return;

            editor.on( 'instanceReady', function() {

                var editable = editor.editable(),
                    lastHeight;

                // Simply set auto height with div wysiwyg.
                if ( editable.isInline() )
                    editor.ui.space( 'contents' ).setStyle( 'height', 'auto' );
                // For framed wysiwyg we need to resize the editor.
                else
                {
                    editor.addCommand( 'autogrow', {
                        exec: function( editor ) {
                            lastHeight = resizeEditor( editor, lastHeight );
                        },
                        modes:{ wysiwyg:1 },
                        readOnly: 1,
                        canUndo: false,
                        editorFocus: false
                    } );

                    var eventsList = { contentDom:1,key:1,selectionChange:1,insertElement:1,mode:1 };
                    for ( var eventName in eventsList ) {
                        editor.on( eventName, function( evt ) {
                            // Some time is required for insertHtml, and it gives other events better performance as well.
                            if ( evt.editor.mode == 'wysiwyg'  ) {
                                setTimeout( function() {
                                    lastHeight = resizeEditor( evt.editor, lastHeight );
                                    // Second pass to make correction upon
                                    // the first resize, e.g. scrollbar.
                                    lastHeight = resizeEditor( evt.editor, lastHeight );
                                }, 100 );
                            }
                        });
                    }

                    // Coordinate with the "maximize" plugin. (#9311)
                    editor.on( 'afterCommandExec', function( evt ) {
                        if ( evt.data.name == 'maximize' && evt.editor.mode == 'wysiwyg' ) {
                            if ( evt.data.command.state == CKEDITOR.TRISTATE_ON ) {
                                var scrollable = getScrollable( editor );
                                scrollable.removeStyle( 'overflow' );
                            }
                            else
                                lastHeight = resizeEditor( editor, lastHeight );
                        }
                    });

                    editor.config.autoGrow_onStartup && editor.execCommand( 'autogrow' );
                }
            });
        }
    });
})();

/**
 * The minimum height that the editor can reach using the AutoGrow feature.
 *
 *		config.autoGrow_minHeight = 300;
 *
 * @since 3.4
 * @cfg {Number} [autoGrow_minHeight=200]
 * @member CKEDITOR.config
 */

/**
 * The maximum height that the editor can reach using the AutoGrow feature. Zero means unlimited.
 *
 *		config.autoGrow_maxHeight = 400;
 *
 * @since 3.4
 * @cfg {Number} [autoGrow_maxHeight=0]
 * @member CKEDITOR.config
 */

/**
 * Whether to have the auto grow happen on editor creation.
 *
 *		config.autoGrow_onStartup = true;
 *
 * @since 3.6.2
 * @cfg {Boolean} [autoGrow_onStartup=false]
 * @member CKEDITOR.config
 */

/**
 * Extra height in pixel to leave between the bottom boundary of content with document size when auto resizing.
 *
 * @since 3.6.2
 * @cfg {Number} [autoGrow_bottomSpace=0]
 * @member CKEDITOR.config
 */

/**
 * Fired when the AutoGrow plugin is about to change the size of the editor.
 *
 * @event autogrow
 * @member CKEDITOR.editor
 * @param {CKEDITOR.editor} editor This editor instance.
 * @param data
 * @param {Number} data.currentHeight The current height of the editor (before resizing).
 * @param {Number} data.newHeight The new height of the editor (after resizing). It can be changed
 * to determine a different height value to be used instead.
 */